add split 15 (year 2015)

data/15.parquet

@@ -1,3 +1,3 @@
 version https://git-lfs.github.com/spec/v1
-oid sha256:86ba6185a10c81695d35197500fe785f55898fbf50e8f5740382f4c4537ac4c3
-size 4640579
+oid sha256:1c9723ccbc46420a651c880bddab8fe71243e635035652d5de3b68b406092e89
+size 4635791